A riser is a pipe extending from a drilling platform on the sea surface to the seabed and serves to effectively extend a subsea well to a surface drilling facility. The riser may be connected at the seabed to a blowout preventer and a wellhead. At the sea surface, the riser may be connected to a drilling ship (or platform). The riser may be used for transporting drilling mud from the borehole to the drill ship and also provides a channel for a drill pipe and other tools extending from the ship to the well head. As the ship is located on the sea surface, the ship will move up and down with the swell on the sea surface. Means are provided to allow vertical movement of the ship within a range of values, while maintaining a tension on the riser. However, these means are not sufficient to compensate for extreme movements of the ship, for example during very severe weather conditions. These compensating means may cease to operate unintentionally resulting in a non compensated ship or floating platform. Therefore, a weak link may be provided in the riser or riser couplings at a predetermined location or elevation which fails or releases under a predefined amount of tensile force, bending moment or combinations thereof on the riser. If a weak link fails or releases, the riser part below the weak link may stay connected to the blowout preventer, while the riser part above the weak link may stay connected to the ship. The sudden release of the upper riser part and its upward momentum may present a serious danger to the drilling ship. The upward movement may be driven further by a positive pressure of gas or fluids inside the riser.